PROVIDENCIALES, Turks and Caicos  Sixty feet below the surface of the aquamarine Caribbean, Maddie, my 12-year-old daughter, glided gently along the reef, her arms crossed in Buddha-like meditation. n To the left, out where the sea dropped off hundreds of feet, a black-tipped shark cruised ominously in the near distance. Closer, a curious parrot fish, a school of yellow-striped grunts, and a bug-eyed squirrel fish swam just an arm’s length away, perhaps hoping for a handout from our group of six divers and our guide. n Directly below us, a green sea turtle chomped on a chunk of coral, oblivious to our presence. I moved in to photograph its sleek head and it didn’t move an inch.

The visibility was more than 80 feet, and we could see other divers from our Beaches Resort boat off in the distance. The tips of the sea anemones fluttered in the mild current and a bright orange tube sponge seemed to jump out from the surrounding coral.

It was a far cry from a recent outing we’d had in Devil’s Lake in southern Wisconsin, about 30 miles from our home in Madison. There, the “viz” — as divers call it — in this murky freshwater lake was a mere five feet, if that.

Maddie Clark, a sixth-grader, got her open water SCUBA certification for the diving trip.

Maddie Clark, a sixth-grader, got her open water SCUBA certification for the diving trip.

It was only this past summer that Maddie, a sixth-grader, had gotten her open water SCUBA certification. Though diving in the Great Lakes can offer great visibility — often well over 60 feet — it can’t compare with the pleasantly warm Caribbean. (Besides, there aren’t any sea turtles, manta rays, lobsters or sharks in Lake Michigan or Superior, which border Wisconsin to the east and north, respectively.)

Back on the surface after her first saltwater dive, Maddie told me and her mother, Kathleen:

“This is great. I never thought I’d see a shark right away. And that turtle was totally cool. Thank you so much for bringing me here.”

Fifty minutes later, after we’d munched on sandwiches and fruit and let dissolved nitrogen gas escape from our bloodstream, we were ready for another go. Maddie did a giant stride into the water, followed by her mother and the rest of the crew.

We dropped to the bottom, swam through a coral tunnel and came upon a colorful lionfish. Known to scientists as the Pterois and native to the Indian and Pacific oceans, this critter has red, white and black bands, fan fins that look like a lion’s manes and — here’s the kicker — poisonous spiky fin rays.

We’d been instructed not to touch anything in the underwater preserve where we were diving, and for this football-sized beast, that was especially true. Its venom, delivered from an array of up to 18 needlelike dorsal fins, is painful and can even cause breathing problems. (Fortunately, it’s usually not fatal.)

Unlike other aquatic creatures that are threatened, lionfish are troublemakers — an invasive species — in this part of the world because they are ferocious predators. That’s why locals are encouraged to capture and eat them.